1. Field of the Invention
The invention is directed to an apparatus for generating acoustic waves of the type having an acoustic transducer with a first electrode serving as a membrane and adjoining an acoustic propagation medium, and a second electrode spaced from the first electrode, between which an electrolyte is situated.
2. Description of the Prior Art
An apparatus of the above type for generating acoustic waves operates according to the thermo-hydraulic principle. Due to the brief heating of the electrically conductive electrolyte situated between the electrodes by a filament voltage that flows as a result of an electrical pulse applied to the electrodes, electrical energy is directly converted into thermal energy of the electrolyte practically loss-free. The thermal expansion of the electrolyte produced by the filament current generates a pressure wave propagates in the acoustic propagation medium adjacent to the first electrode. Accordingly, the apparatus can be utilized, for example, for generating shock waves as employed in medicine in lithotripsy or in pain therapy.
An apparatus of the type initially described is disclosed in German OS 197 02 593. The apparatus has a first electrode which is a solid and a second, thin electrode serving as membrane between which the electrolyte is situated.
A disadvantage of the apparatus for generating acoustic waves disclosed in German OS 197 02 593 the use of x-rays to locate an object to be irradiated with sound with the apparatus—as is standard in lithotripsy for locating calculi—can ensue only when the apparatus is “behind” the x-rays. Consequently, the possibilities of X-ray locating at the apparatus are limited. This means that an attending physician can only see a part of the therapy region in the X-ray exposures for medical applications in lithotripsy.